German Patent No. DE 10 2006 057 247 relates to a supercharging device in which thermal energy is withdrawn from the exhaust gas of an internal combustion engine via a steam circuit and converted partially into mechanical and electrical energy by a turbine. Unutilized waste heat is discharged to the environment by a separate condenser. A supercharging device is used in particular for supercharging an internal combustion engine. At least one exhaust gas heat exchanger of a circuit of a working medium is situated in the exhaust system. A delivery unit is connected in the circuit of the working medium upstream from the at least one exhaust gas heat exchanger. The circuit of the working medium contains at least one turbine part, via which at least one compressor part situated in the intake system of the internal combustion engine is driven.
A publication “BMW four-cylinder utilizes waste heat for increased performance-engine with turbine” is known from the magazine “Auto Motor und Sport,” volume 10, page 26/2005. According to this publication, an internal combustion engine converts approximately two-thirds of the energy contained in the fuel into waste heat, which is either taken up into the cooling system of the internal combustion engine or discharged through the exhaust system of the internal combustion engine. In internal combustion engines, the previously unutilized waste heat may be used for increasing the efficiency by up to 15%. To that end, a 1.8-liter four-cylinder engine is coupled to a steam turbine having a two-stage design which acts on the crank shaft of the 1.8-liter four-cylinder engine. The hot steam is generated by heat exchangers which are accommodated close to the exhaust pipe in the exhaust system of the internal combustion engine. A water circuit may be used to branch cooling fluid off from the cooling circuit of the internal combustion engine. The drive of the crank shaft makes it possible to either increase the power and the torque or reduce the specific fuel consumption significantly.